40 million Americans now have student loan debt

Carrying tens of thousands of dollars in student loan debt has become the new normal.

Thanks to climbing tuition and inadequate college savings, 40 million Americans now have at least one outstanding student loan, according to new analysis from credit bureau Experian. That's up from 29 million consumers in 2008.

On average, borrowers are carrying roughly four student loans each, up from less than three in 2008. Meanwhile, the average balance has increased to $29,000 from $23,000.

"Student loans are the only credit vehicle where a lender continues to extend credit year after year without knowing the person's ability, or even willingness, to pay," said Michele Raneri, vice president of analytics at Experian.

The one positive aspect of all this is that if you're in a strong enough financial situation to make on-time payments, having a student loan can help you establish and improve your credit early on.

But if you're not, it can have the opposite impact.

"Missing payments affects your credit just like any other debt, [and] payment history is the most important factor in credit scores," said Rod Griffin, Experian's director of public education.